The invention relates to a method for transmitting data in networks over data lines.
Methods for data compression have been known for some time and serve to reduce the volume of data before it is otherwise processed, so that it requires less memory or can be transmitted more quickly over communication lines.
Thus the following examples are known processes applying current techniques:
EP 0 933 B76 describes a method of compressing and transmitting data in unreliably functioning networks. After the first communication between two interacting terminals, Terminal 2 sends a defined algorithm for data compression to Terminal 1. Data is compressed according to this algorithm and returned to Terminal 2, where data is unpacked according to the originally sent algorithm.
U.S. Pat. No. 5,822,524 describes a process for transmitting multimedia data, such as videos, in a network. Multimedia data is called up from a server via a user terminal and sent compressed and digitalized in such a way that the user terminal's buffer, which can normally save 1 to 5 video images, is always full. Video data is thus not linked to a continuous or medial data stream.
U.S. Pat. No. 5,564,001 also describes a method of transmitting multimedia data in networks with limited bandwidth, which includes telecommunication cable networks. Here, multimedia data is separated into important and less important multimedia information according to a psychographics parameter. The data can thereafter be at least partially compressed. After transmission to the user, the compressed data is decompressed and rejoined with the data which was sent in uncompressed form.
EP 0 852 445 discloses a method to optimize bandwidth for compressed multimedia data streams for transmission in networks. Compressed data blocks are marked before being sent so that each block's marker includes the data block's enclosed data volume, information relevant to compression/decompression, and the point at which each data block is to be reinserted into the entire data composite. In addition, before data transmission, a server detects the recipient's minimum buffer capacity and minimum number of receivable data blocks. This information, combined with the transmission rate of the compressed data blocks, allows calculation of an optimal stream of compressed data blocks to the recipient's buffer, and the compressed data blocks can be transmitted with a specific minimum rate to keep the recipient's buffer running just barely above idle. This transmission method guarantees transmission of compressed data blocks over an appropriate bandwidth, because available bandwidth depends on the recipient's buffer capacity. A large receiving buffer increases available bandwidth; a faster transmission of compressed data blocks ensues to prevent the buffer from idling and thus avoid momentary freeze images. In contrast, data block transmission decreases for a small buffer to prevent a superimposition of the individual images.
The known methods of transmitting compressed data reduce data volume for transmission by compressing data to be transmitted; however, they cannot prevent the fact that sender and recipient of this data have no access to data available in the network during data transmission. The recipient is blocked for the duration of data transmission and incapable of communication with other end devices or the central processing unit of each network.
Because data volume intended for transmission nevertheless continually increases in networks (for example, extensive print jobs, high-resolution images, or multimedia data information), this problem cannot be ignored.